Hydrophone cable



United States Patent Ofice 3,434,104 Patented Mar. 18, 1969 1 ClaimABSTRACT OF THE DISCLOSURE This invention provides a new type ofhydrophone cable section wherein a body of cellular material such asfoamed polyurethane is provided with cavities in its exterior surface,in which crystal detectors are recessed, and the body is enclosed by awaterproof jacket. Flotation liquid is contained in the space betweenthe outer jacket and the body, and strain members and electricalconducting wires are enclosed within the body, the combination producinga cable section which will not lose its entire flotation ability nor itsability to protect the crystal detectors and wires even though the outerjacket may be ruptured by contact with external bodies.

This invention relates to a hydrophone cable and more particularly to ahydrophone cable constructed of a plurality of sections which are soconstructed and arranged as to provide maximum protection to the sensingdevices carried thereby.

It is a general object of the present invention to produce a new andimproved hydrophone cable section of the character described in thepreceding paragraph.

It is a more specific object of the invention to provide a hydrophonecable section which includes a cellular interior body possessingflotation characteristics and in which a plurality of crystal detectorsare located in recessed portions of the body so as to be protected fromdamage by encounter with external objects.

Hydrophone cables, often of considerable length, are utilized ratherextensively in the seismic exploration for offshore oil deposits. Theordinary cable section is provided with a waterproof exterior coverwhich encloses a flotation liquid, usually kerosene, and also enclosesthe electrical sensing devices such as crystal detectors andaccompanying wiring. Additionally, a strain member usually in the formof a wire cable, extends through the sections in order to bear thestrain when towing long lengths of hydrophone cable through the water.In the event a cable section of the type just described encounters aforeign object so as to rupture the outer cover, the flotation liquid islost and, additionally, water is allowed to enter, damaging thecomponents and also destroying the flotation characteristics of thecable through loss of the flotation liquid. As a result, the hydrophonecable may sink to the bottom of the body of water being explored and befurther damaged or lost.

According to the present invention, however, the hydro phone cablesection includes a central core or body of cellular material surroundedby an outer waterproof jacket, with kerosene or other flotation liquidbeing provided in the space between the body and the outer cover.Additionally, the crystal detectors are enclosed in a separatewaterproof cover or jacket and the conducting wires pass through theinterior of the body. Accordingly, even though such a hydrophone cablesection should encounter a sunken object and the outer cover rupturedwith the resultant loss of flotation fluid, the inherent flotationcharacteristics of the cellular body serve to provide buoyancy for theapparatus and the separate waterproof cover enclosing the crystaldetectors prevent their damage by entering sea water. The conductorwires extending through a central portion of the body are similarlyprotected from damage or corrosion by salt water with the result thathydrophone cables constructed in accordance with the present inventionexhibit an ability to withstand damage without destruction of the cableand to continue to function efficiently and effectively even aftersuffering damage which would render inoperable hydrophone cables ofother construction.

The foregoing objects and advantages of the invention will be readilyapparent from the following description and drawings, in which:

FIGURE 1 is an elevational view of a hydrophone cable made up of aplurality of hydrophone cable sections;

FIGURE 2 is an enlarged plan view of a single hydrophone cable section;

FIGURE 3 is an enlarged vertical longitudinal sectional view of aportion of a cable section;

FIGURE 4 is a horizontal longitudinal section of the cable shown inFIGURE 3; and

FIGURE 5 is a transverse vertical section taken along line 55 of FIGURE4.

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail a specific embodiment of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit theinvention to the embodiment illustrated. The scope of the invention willbe pointed out in the appended claim.

Referring now to the drawings, there is shown a hydrophone cable 10which is made up of a number of cable sections 11. Each cable sectionmay be from 300 to 900 feet long and the hydrophone cable 10 is made upof a plurality of typical sections, each approximately 600 feet long,there being some twelve or more sections in each complete cable therebyproviding an over-all length in excess of 7,000 feet. In a hydrophonecable of the type shown in FIGURE 1 there are normally about 24 detectorcircuits plus spare circuits, making a total on all of 30 to 40circuits. As shown in FIGURE 2, two circuits are provided in each cablesection, namely, detector circuits 12 and 13. Each circuit may have from1 to 30 crystal detectors electrically connected in parallel, in series,or in series parallel. The detectors are connected to the high side of astep down transformer (not shown) and the low side of such transformeris then connected to the appropriate circuit.

The cable section of the present invention includes a body 14 ofcellular material (preferably foamed polyrurethane) which extendsgenerally from end to end of the cable section. The body 14 is providedwith a central opening 15 through the center of which extends a strainmember in the form of a cable 16. The strain members of each section areconnected together so that the cable bears the strain of towing theentire hydrophone assembly through the water. A waterproof jacket,preferably of polyvinyl chloride encloses the cable 16.

The wires interconnecting the various circuits are shown as at 18 andsurround the jacket 17. A second polyvinyl jacket 19 surrounds the outerperiphery of the wires so as to protect them from any salt water leakinginto the cable section.

Extending along an exterior surface of the cellular body 14 is a cavity20 in which is located a crystal detector 21 of usual construction. Thedetector 21 includes a cavity 22 beneath the detector so as to permitthe same to deflect thereinto when pressure waves encounter thehydrophone cable section. From each crystal detector 21 wires 23 extendand are wrapped around a connector 24. The wires eventually extend intoand are connected to the circuit wires 18 extending along the interiorof the cellular section. A waterproof jacket 25, again preferably ofpolyvinyl chloride, encloses each of the crystal detectors but is soarranged as to transmit to the crystal detectors shock waves resultingfrom explosions or the like utilized in seismic exploration.

The outer surface of the hvdrophone section comprises an outer cover 26,again of polvvinyl chloride, which is spaced from the body 14 by meansnot shown so as to provide a space 27 therebetween. A flotation fluid,usually kerosene 28, fills the space 27 and provides the primary buoyantforce.

The hydrophone cable of the present invention is used in the same manneras previous hydrophone cable. However, it will be seen that if the outercover 26 is ruptured, such as by striking a submerged object, theresulting loss of the flotation liquid 28 will not deprive the cablesection of its entire buoyancy, the cellular structure of the body 14providing reserve buoyancy and thus preventing the entire hydrophonecable from sinking to the bottom. Even though the space 27 be flooded bysalt water, the jacket 25 will continue to protect the crystal detectorsfrom salt water and the jackets 17 and 19 protect the wires and cablefrom the damaging effects of salt water immersion so that the entirehydrophone cable assembly may continue to be used and will continue tofunction successfully even after suffering damage which would renderordinary hydrophone cables inoperative.

Thus, it will be readily apparent to those skilled in the art to whichthe invention pertains that the present invention provides a hydrophonecable of unusual durability coupled with the capability of continuedfunctioning even after extensive damage and flooding.

We claim:

1. A hydrophone cable construction comprising a plurality of cablesections, each section including an elongated body of foamed cellularmaterial, an opening extending centrally and longitudinally through thebody, a strain cable extending continuously through said centralopening, a first waterproof jacket enclosing the cable, a plurality ofelectrical conductors in said central opening and surrounding saidjacket, a second waterproof jacket enclosing said electrical conductors,a crystal detector positioned in a cavity formed in the exterior surfaceof the body, a waterproof cover enclosing said crystal detector, meanselectrically connecting said crystal detector to said electricalconductors, a third waterproof jacket enclosing the body and spacedtherefrom, and a. fluid having a specific gravity of less than 1 in saidspace to provide buoyancy to said section.

References Cited UNITED STATES PATENTS 2,864,073 12/1958 Harris 34072,923,916 2/1960 Woodworth 3407 3,353,150 11/1967 Jacox 34010 RODNEY D.BENNETT, Primary Examiner.

C. E. WANDS, Assistant Examiner.

U.S. C1. X.R. 340-10

